Virgaurols A–D: Novel Asymmetric Eremophilane Dimers from the Roots of Ligularia virgaurea

Abstract

Abstract Virgaurols A–D (1–4), four novel asymmetric eremophilane sesquiterpene dimers were isolated from the roots of Ligularia virgaurea. Especially, virgaurols A (1) and B (2) possessed novel carbon skeleton in which the two sesquiterpene units are uniquely connected by a single C–C bond directly. The structures of these dimers were determined on the basis of comprehensive spectral analysis. Compounds 1 and 3 were found to exhibit weak cytotoxicity against human leukemia (HL-60), human hepatoma (SMMC-7721), and human cervical carcinoma (HeLa) cells.